The 21-year-old, who was a youth product at Sporting Lisbon, before coming to England and playing in non league, signed for Jimmy Floyd-Hasselbaink's side in July.
And he has so far made five appearances for the club.
However, Albion, who signed Castro in 2021, have now recalled the midfielder from his loan spell.
It is not known whether this is down to injury - or whether he is set to be part of Steve Bruce's first team plans.
